Liquid crystal composition and liquid crystal device

ABSTRACT

A liquid crystal composition having a negative dielectric anisotropy that includes two components, wherein the first component is a specific two-ring compound having phenylene, two hydrogens of which are replaced by fluorine, and the second component is a specific four-ring compound having phenylene, one hydrogen of which is replaced by fluorine, and a liquid crystal display device including the composition.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Japanese PatentApplication No. JP 2006-198658, filed Jul. 20, 2006, which is expresslyincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a liquid crystal composition suitable for usein an active matrix (AM) device, and an AM device containing thecomposition. In particular, the invention relates to a liquid crystalcomposition having a negative dielectric anisotropy, and to a devicehaving an IPS (in-plane switching) mode or a VA (vertical alignment)mode containing the composition.

2. Related Art

In a liquid crystal display device, classification based on an operatingmode of liquid crystals includes phase change (PC), twisted nematic(TN), super twisted nematic (STN), electrically controlled birefringence(ECB), optically compensated bend (OCB), in-plane switching (IPS),vertical alignment (VA), and so forth. Classification based on a drivingmode includes a passive matrix (PM) and an active matrix (AM). PM isfurther classified into static, multiplex and so forth, and AM isclassified into a thin film transistor (TFT), a metal insulator metal(MIM) and so forth. TFT is further classified into amorphous silicon andpolycrystal silicon. The latter is classified into a high temperaturetype and a low temperature type according to a production process.Classification based on a light source includes a reflection typeutilizing a natural light, a transmission type utilizing a backlight anda semi-transmission type utilizing both the natural light and thebacklight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes the relationship between the general characteristics of thetwo. The general characteristics of the composition will be explainedfurther based on a commercially available AM device. A temperature rangeof a nematic phase relates to the temperature range in which the devicecan be used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or more and a desirable minimum temperature isapproximately −10° C. or less. The viscosity of the composition relatesto the response time of the device. A short response time is desirablefor displaying a moving image. Accordingly, a small viscosity of thecomposition is desirable. A small viscosity at a low temperature is moredesirable.

TABLE 1 General Characteristics of a Liquid Crystal Composition and anAM Device No. General Characteristics of a Composition GeneralCharacteristics of an AM Device 1 Temperature range of a nematic phaseis wide Usable temperature range is wide 2 Viscosity is small¹⁾ Responsetime is short 3 Optical anisotropy is suitable Contrast ratio is large 4An absolute value of dielectric anisotropy is large Threshold voltage islow, electric power consumption is small, and a contrast ratio is large5 Specific resistance is large Voltage holding ratio is large and acontrast ratio is large 6 It is stable to ultraviolet light and heatService life is long ¹⁾A liquid crystal composition can be injected intoa cell in a short time.

The optical anisotropy of the composition relates to the contrast ratioof the device. Devices having a VA mode, an IPS mode, and so forthutilize electrically controlled birefringence. In order to maximize thecontrast ratio of a device having a VA mode, an IPS mode, and so forth,a product (Δn·d) of the optical anisotropy (Δn) of the composition andthe cell gap (d) of the device is designed to be a constant value.Examples of the value include from 0.30 to 0.40 μm (VA mode) and from0.20 to 0.30 μm (IPS mode). Since the cell gap (d) is generally from 2to 6 μm, the optical anisotropy of the composition is generally from0.05 to 0.16. A large dielectric anisotropy of the compositioncontributes to a low threshold voltage, a small electric powerconsumption and a large contrast ratio of the device. Accordingly, alarge dielectric anisotropy is desirable. A large specific resistance ofthe composition contributes to a large voltage holding ratio and a largecontrast ratio of the device. Accordingly, a composition having a largespecific resistance is desirable at room temperature and also at a hightemperature in the initial stage. A composition having a large specificresistance at room temperature and also at a high temperature after ithas been used for a long time is desirable. The stability to anultraviolet ray and heat of the composition relates to the service lifeof the liquid crystal device. The service life of the device is longwhen the stability is high. These characteristics are preferred for anAM device used for a liquid crystal projector, a liquid crystaltelevision and so forth.

A composition having a positive dielectric anisotropy is used in an AMdevice having a TN mode. A composition having a negative dielectricanisotropy is used in an AM device having a VA mode. A compositionhaving a positive or negative dielectric anisotropy is used in an AMdevice having an IPS mode. Examples of a liquid crystal compositionhaving a negative dielectric anisotropy are disclosed in the followingpatent documents: JP H9-183974 A/1997, JP H10-176167 A/1998, JPH11-116512 A/1999, JP H11-140447 A/1999, JP 2000-96055 A/2000 and JP2003-327965 A/2003.

A desirable AM device is characterized as having a usable temperaturerange that is wide, a response time that is short, a contrast ratio thatis large, a threshold voltage that is low, a voltage holding ratio thatis large, a service life that is long, and so forth. Even a onemillisecond shorter response time is desirable. Thus, the compositionhaving characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a large optical anisotropy, a negatively large dielectric anisotropy, alarge specific resistance, a high stability to an ultraviolet light, ahigh stability to heat, and so forth is especially desirable.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition having a negativedielectric anisotropy including two components, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by Formula (1), and the second component is at least onecompound selected from the group of compounds represented by Formula(2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; Z¹ is a single bond or —(CH₂)₂—; and Y¹ and Y² are eachindependently hydrogen or fluorine.

The invention also concerns a liquid crystal display device thatincludes the liquid crystal composition and so forth.

DETAILED DESCRIPTION OF THE INVENTION

The terms used in the specification and claims are defined as follows:The liquid crystal composition and/or the liquid crystal display deviceof the invention may occasionally be expressed simply as “thecomposition” or “the device,” respectively. A liquid crystal displaydevice is a generic term for a liquid crystal display panel and a liquidcrystal display module. The “liquid crystal compound” is a generic termfor a compound having a liquid crystal phase such as a nematic phase, asmectic phase and so forth, and also for a compound having no liquidcrystal phase but being useful as a component of a composition. Theuseful compound contains a 6-membered ring such as 1,4-cyclohexylene and1,4-phenylene, and a rod-like molecular structure. An optically activecompound may occasionally be added to the composition. Even in the casewhere the compound is a liquid crystal compound, the compound isclassified into an additive. At least one compound selected from a groupof compounds represented by Formula (1) may be abbreviated to “thecompound (1).” The term “the compound (1)” means one compound or two ormore compounds represented by Formula (1). Other compounds representedby the other formulas are applied with the same rules. The term“arbitrary” means not only an arbitrary position but also an arbitrarynumber, and the case where the number is zero is not included.

A higher limit of a temperature range of a nematic phase may beabbreviated to “a maximum temperature.” A lower limit of a temperaturerange of a nematic phase may be abbreviated to “a minimum temperature.”“A specific resistance is large” means that the composition has a largespecific resistance at room temperature and also at a high temperaturein the initial stage, the composition has a large specific resistance atroom temperature and also at a high temperature even after it has beenused for a long time. “A voltage holding ratio is large” means that adevice has a large voltage holding ratio at room temperature and also ata high temperature in the initial stage, the device has a large voltageholding ratio at room temperature and also at a high temperature evenafter it has been used for a long time. In the description of thecharacteristics, such as optical anisotropy, the characteristics of thecomposition such as the optical anisotropy and so forth are valuesmeasured in the methods disclosed in Examples. The first component isone compound or two or more compounds. “A ratio of the first component”means the percentage by weight (% by weight) of the first componentbased on the total weight of liquid crystal composition. A ratio of thesecond component and so forth are applied with the same rule. A ratio ofan additive mixed with the composition means the percentage by weight (%by weight) based on the total weight of liquid crystal composition.

The symbol R¹ is used for many compounds in the chemical formulas forthe component compounds. R¹ may be identical or different in thesecompounds. In one case, for example, R¹ of the compound (1) is ethyl andR¹ of the compound (2) is ethyl. In another case, R¹ of the compound (1)is ethyl and R¹ of the compound (2) is propyl. This rule is alsoapplicable to the symbols R², R³ and so forth.

One advantage of the invention is to provide a liquid crystalcomposition that satisfies at least one characteristic among thecharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a negatively large dielectric anisotropy, a largespecific resistance, a high stability to ultraviolet light, a highstability to heat and so forth. Another advantage of the invention is toprovide a liquid crystal composition that is properly balanced regardingat least two characteristics among the many characteristics. Stillanother advantage of the invention is to provide a liquid crystaldisplay device that includes the liquid crystal composition. One aspectof the invention is to provide a liquid crystal composition that has alarge optical anisotropy, a large negative dielectric anisotropy, a highstability to ultraviolet light and so forth, and is to provide an AMdevice that has a short response time, a large voltage holding ratio, alarge contrast ratio, a long service life and so forth.

The invention includes the following features:

1. A liquid crystal composition having a negative dielectric anisotropyincluding two components, wherein the first component is at least onecompound selected from the group of compounds represented by Formula(1), and the second component is at least one compound selected from thegroup of compounds represented by Formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; Z¹ is a single bond or —(CH₂)₂—; and Y¹ and Y² are eachindependently hydrogen or fluorine.

2. A liquid crystal composition having a negative dielectric anisotropyincluding two components, wherein the first component is at least onecompound selected from the group of compounds represented by Formulas(1-1) and (1-2), and the second component is at least one compoundselected from the group of compounds represented by Formula (2-1):

wherein R³ and R⁵ are each independently alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons; and R⁴ is alkyl having 1 to 12 carbonsor alkoxy having 1 to 12 carbons.

3. The liquid crystal composition according to item 2, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by Formula (1-1), and the second component is at least onecompound selected from the group of compounds represented by Formula(2-1).

4. The liquid crystal composition according to item 2, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by Formula (1-2), and the second component is at least onecompound selected from the group of compounds represented by Formula(2-1).

5. The liquid crystal composition according to item 2, wherein the firstcomponent is a mixture of at least one compound selected from the groupof compounds represented by Formula (1-1) and at least one compoundselected from the group of compounds represented by Formula (1-2), andthe second component is at least one compound selected from the group ofcompounds represented by Formula (2-1).

6. The liquid crystal composition according to any one of items 1 to 5,wherein the ratio of the first component is from approximately 25% byweight to approximately 65% by weight and the ratio of the secondcomponent is from approximately 5% by weight to approximately 40% byweight, based on the total weight of the liquid crystal composition.

7. The liquid crystal composition according to any one of items 1 to 6,wherein the composition further includes at least one compound selectedfrom the group of compounds represented by Formulas (3-1) and (3-2) as athird component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; Ring A is 1,4-cyclohexylene or 1,4-phenylene; and Z² and Z³are each independently a single bond, —(CH₂)₂—, —CH═CH—, —COO— or —OCO—.

8. The liquid crystal composition according to item 7, wherein the thirdcomponent is at least one compound selected from the group of compoundsrepresented by Formula (3-1).

9. The liquid crystal composition according to item 7, wherein the thirdcomponent is at least one compound selected from the group of compoundsrepresented by Formula (3-2).

10. The liquid crystal composition according to item 7, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by Formula (3-1) and at least onecompound selected from the group of compounds represented by Formula(3-2).

11. The liquid crystal composition according to any one of items 1 to 6,wherein the composition further includes at least one compound selectedfrom the group of compounds represented by Formulas (3-1-1) and (3-2-1)as a third component:

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons; and R⁴ is alkyl having 1 to 12 carbons or alkoxy having 1 to 12carbons.

12. The liquid crystal composition according to item 11, wherein thethird component is at least one compound selected from the group ofcompounds represented by Formula (3-1-1).

13. The liquid crystal composition according to item 11, wherein thethird component is at least one compound selected from the group ofcompounds represented by Formula (3-2-1).

14. The liquid crystal composition according to item 11, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by Formula (3-1-1) and at least onecompound selected from the group of compounds represented by Formula(3-2-1).

15. The liquid crystal composition according to any one of items 7 to14, wherein the ratio of the third component is from approximately 10%by weight to approximately 65% by weight based on the total weight ofthe liquid crystal composition.

16. The liquid crystal composition according to any one of items 1 to15, wherein the composition further includes at least one compoundselected from the group of compounds represented by Formulas (4-1) and(4-2) as a fourth component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; and Y¹, Y² and Y³ are each independently hydrogen orfluorine.

17. The liquid crystal composition according to item 16, wherein thefourth component is at least one compound selected from the group ofcompounds represented by Formula (4-1).

18. The liquid crystal composition according to item 16, wherein thefourth component is at least one compound selected from the group ofcompounds represented by Formula (4-2).

19. The liquid crystal composition according to item 16, wherein thefourth component is a mixture of at least one compound selected from thegroup of compounds represented by Formula (4-1) and at least onecompound selected from the group of compounds represented by Formula(4-2).

20. The liquid crystal composition according to any one of items 1 to15, wherein the composition further includes at least one compoundselected from the group of compounds represented by Formulas (4-1-1) and(4-2-1) as a fourth component:

wherein R³ and R⁵ are each independently alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons.

21. The liquid crystal composition according to item 20, wherein thefourth component is at least one compound selected from the group ofcompounds represented by Formula (4-1-1).

22. The liquid crystal composition according to item 20, wherein thefourth component is at least one compound selected from the group ofcompounds represented by Formula (4-2-1).

23. The liquid crystal composition according to item 20, wherein thefourth component is a mixture of at least one compound selected from thegroup of compounds represented by Formula (4-1-1) and at least onecompound selected from the group of compounds represented by Formula(4-2-1).

24. The liquid crystal composition according to any one of items 16 to23, wherein the ratio of the fourth component is from approximately 5%by weight to approximately 30% by weight based on the total weight ofthe liquid crystal composition.

25. The liquid crystal composition according to any one of items 1 to24, wherein the composition has a maximum temperature of a nematic phaseof approximately 70° C. or more, an optical anisotropy (25° C.) at awavelength of 589 nm of approximately 0.10 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz of approximately −2 or less.

26. A liquid crystal display device that includes the liquid crystalcomposition according to any one of items 1 to 25.

27. The liquid crystal display device according to item 26, wherein theliquid crystal display device has an operation mode of a VA mode or anIPS mode, and has a driving mode of an active matrix mode.

The invention further includes: (1) the composition described above,wherein the composition further includes an optically active compound;(2) the composition described above, wherein the composition furtherincludes an additive, such as an antioxidant, an ultraviolet lightabsorbent and/or an antifoaming agent; (3) an AM device including thecomposition described above; (4) a device having an IPS or VA mode,including the composition described above; (5) a device of atransmission type, including the composition described above; (6) use ofthe composition described above as a composition having a nematic phase;and (7) use as an optically active composition by adding an opticallyactive compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, the main characteristics of the componentcompounds and the main effects of the compounds on the composition willbe explained. Third, a desirable ratio of the component compounds andthe basis thereof will be explained. Fourth, a desirable embodiment ofthe component compounds will be explained. Fifth, examples of thecomponent compound will be shown. Sixth, additives that may be added tothe composition will be explained. Seventh, the preparation methods ofthe component compound will be explained. Lastly, use of the compositionwill be explained.

First, the constitution of component compounds in the composition willbe explained. The composition of the invention is classified into thecomposition A and the composition B. The composition A may furtherinclude another liquid crystal compound, an additive, an impurity, andso forth. Another liquid crystal compound is different from the compound(1), the compound (2), the compound (3-1), the compound (3-2), thecompound (4-1) and the compound (4-2). Such another compound is mixedwith the composition for the purpose of adjusting the characteristics ofthe composition. Among another liquid crystal compounds, an amount of acyano compound is desirably small from the viewpoint of stability toheat or ultraviolet light. The ratio of the cyano compound is moredesirably 0% by weight. The additive includes an optically activecompound, an antioxidant, an ultraviolet light absorbent, a coloringmatter, an antifoaming agent and so forth. The impurity is a compoundand so forth contaminated in the process such as the synthesis of acomponent compound and so forth.

The composition B consists essentially of the compounds selected fromthe compound (1), the compound (2), the compound (3-1), the compound(3-2), the compound (4-1) and the compound (4-2). The term “essentially”means that the composition does not contain a liquid crystal compoundwhich is different from these compounds. The term “essentially” alsomeans that the composition may further contain the additive, theimpurity, and so forth. The components of the composition B are fewerthan those of the composition A. The composition B is preferable to thecomposition A from the viewpoint of costs. The composition A ispreferable to the composition B, because characteristics of thecomposition A can be further adjusted by mixing with other liquidcrystal compounds.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the characteristics of composition will beexplained. The main characteristics of the component compounds aresummarized in Table 2 according to the advantages of the invention. InTable 2, the symbol “L” represents large or high, the symbol “M”represents a middle degree, and the symbol “S” represents small or low.The symbols L, M and S are classification based on qualitativecomparison among the component compounds.

TABLE 2 Characteristics of Compounds Compound (1) (2) (3-1) (3-2) (4-1)(4-2) Maximum S L M M M M Temperature Viscosity S M M-L M-L S S OpticalM L M M-L M L Anisotropy Dielectric M-L¹ S M-L¹ M¹ S S AnisotropySpecific L L L L L L Resistance ¹The value of dielectric anisotropy isnegative, and the symbol shows magnitude of an absolute value.

The main effects of the component compounds to the characteristics ofthe composition upon mixing the component compounds to the compositionare as follows: The compound (1) increases the absolute value of thedielectric anisotropy. The compound (2) increases the maximumtemperature and increases the optical anisotropy. The compound (3-1)increases the optical anisotropy and increases the absolute value of thedielectric anisotropy. The compound (3-2) increases the opticalanisotropy and decreases the minimum temperature. The compounds (4-1)and (4-2) decrease the minimum temperature and decrease the viscosity.

Third, desirable ratios of the component compounds and the basistherefor will be explained. A desirable ratio of the first component isapproximately 25% by weight or more for increasing the absolute value ofthe dielectric anisotropy, and is approximately 65% by weight or lessfor decreasing the minimum temperature. A more desirable ratio is fromapproximately 30% by weight to approximately 60% by weight. Aparticularly desirable ratio is from approximately 35% by weight toapproximately 55% by weight.

A desirable ratio of the second component is approximately 5% by weightor more for increasing the maximum temperature and increasing theoptical anisotropy, and is approximately 40% by weight or less fordecreasing the minimum temperature. A more desirable ratio is fromapproximately 5% by weight to approximately 35% by weight. Aparticularly desirable ratio is from approximately 10% by weight toapproximately 30% by weight.

The third component is suitable for preparing a composition having aparticularly large optical anisotropy and a large absolute value of adielectric anisotropy. A desirable ratio of the third component is fromapproximately 10% by weight to approximately 65% by weight. A moredesirable ratio is from approximately 15% by weight to approximately 60%by weight. A particularly desirable ratio is from approximately 20% byweight to approximately 55% by weight.

The fourth component is suitable for preparing a composition having aparticularly small viscosity. A desirable ratio of the fourth componentis from approximately 5% by weight to approximately 30% by weight. Amore desirable ratio is from approximately 10% by weight toapproximately 25% by weight. A particularly desirable ratio is fromapproximately 10% by weight to approximately 20% by weight.

In the composition A, a desirable total ratio of the first component,the second component, the third component and the fourth component isapproximately 70% by weight or more for obtaining good characteristics.A more desirable total ratio is approximately 90% by weight or more. Inthe composition B described above, a total ratio of the four componentsis 100% by weight.

Fourth, a desirable embodiment of the component compound will beexplained. R¹ and R are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine. Desirable R¹ is linear alkyl having 1 to 10 carbons forincreasing the stability to ultraviolet light and heat. Desirable R² islinear alkoxy having 1 to 10 carbons for increasing the absolute valueof the dielectric anisotropy. R³ and R⁵ are each independently alkylhaving 1 to 12 carbons or alkenyl having 2 to 12 carbons. Desirable R³and R⁵ are linear alkyl having 1 to 10 carbons for increasing thestability to ultraviolet light and heat. R⁴ is alkyl having 1 to 12carbons or alkoxy having 1 to 12 carbons. Desirable R⁴ is linear alkoxyhaving 1 to 10 carbons for increasing the absolute value of thedielectric anisotropy.

Desirable alkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,or octyl. More desirable alkyl are ethyl, propyl, butyl, pentyl, orheptyl for decreasing the viscosity.

Desirable alkoxy are methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy, or heptyloxy. More desirable alkoxy are methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl are vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl. More desirablealkenyl are vinyl, 1-propenyl, 3-butenyl, or 3-pentenyl for decreasingthe viscosity. A desirable configuration of —CH═CH— in these alkenylsdepends on the position of a double bond. Trans is desirable in thealkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl, and 3-hexenyl for decreasing the viscosity. Cis is desirablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thesealkenyls, linear alkenyl are preferable to branched alkenyl.

Preferred examples of alkenyl, arbitrary hydrogen of which are replacedby fluorine, include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More preferred examples thereof include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

Ring A is 1,4-cyclohexylene or 1,4-phenylene. Desirable ring A is1,4-phenylene for increasing the optical anisotropy. On theconfiguration of 1,4-cyclohexylene in the compounds, trans is preferableto cis for increasing the maximum temperature.

Z¹ is a single bond or —(CH₂)₂—. Desirable Z¹ is a single bond fordecreasing the viscosity. Z² and Z³ are each independently a singlebond, —(CH₂)₂—, —CH═CH—, —COO— or —OCO—. Desirable Z² and Z³ are asingle bond for decreasing the viscosity.

Y¹, Y² and Y³ are each independently hydrogen or fluorine. Desirable Y¹,Y² and Y³ are fluorine for decreasing the minimum temperature.

Fifth, examples of the component compound will be shown. In thedesirable compounds described below, R⁶ and R⁷ are linear alkyl having 1to 12 carbons. R⁸ is linear alkoxy having 1 to 12 carbons. In thesecompounds, trans is preferable to cis for the configuration of1,4-cyclohexylene for increasing the maximum temperature.

Desirable compounds (1) are the compounds (1-1-1) and (1-2-1). A moredesirable compound (1) is the compound (1-1-1). A desirable compound (2)is the compounds (2-1-1). Desirable compounds (3-1) are the compound(3-1-1-1), the compound (3-1-2) and the compound (3-1-3). A moredesirable compound (3-1) is the compounds (3-1-1-1). Desirable compounds(3-2) are the compound (3-2-1-1), the compound (3-2-2) and the compound(3-2-3). A more desirable compound (3-2) is the compounds (3-2-1-1). Adesirable compound (4-1) is the compound (4-1-1-1). Desirable compounds(4-2) are the compound (4-2-1-1) and the compound (4-2-2). A moredesirable compound (4-2) is the compound (4-2-1-1).

Sixth, additives capable of being mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, anantifoaming agent and so forth. An optically active compound is mixed inthe composition for inducing a helical structure of liquid crystal toprovide a twist angle. Examples of the optically active compound includethe compounds (5-1) to (5-4) below. A desirable ratio of the opticallyactive compound is approximately 5% by weight or less, and a moredesirable ratio thereof ranges from approximately 0.01% by weight toapproximately 2% by weight.

An antioxidant is mixed with the composition in order to avoid adecrease in specific resistance caused by heating in the air, or tomaintain a large voltage holding ratio at room temperature and also at ahigh temperature even after the device has been used for a long time.

Preferred examples of the antioxidant include the compound (6):

wherein n is an integer of from 1 to 9. In the compound (6), desirable nare 1, 3, 5, 7, or 9. More desirable n are 1 or 7. When n is 1, thecompound (6) has a large volatility, and is effective in preventing thedecrease of specific resistance caused by heating in the air. When n is7, the compound (6) has a small volatility, and is effective inmaintaining a large voltage holding ratio at room temperature and alsoat a high temperature even after the device has been used for a longtime. A desirable ratio of the antioxidant is approximately 50 ppm ormore for obtaining the advantage thereof and is approximately 600 ppm orless for preventing the maximum temperature from being decreased andpreventing the minimum temperature from being increased. A moredesirable ratio thereof ranges from approximately 100 ppm toapproximately 300 ppm.

Preferred examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer, such as an amine having steric hindranceis also desirable. A desirable ratio of the absorbent and the stabilizeris approximately 50 ppm or more for obtaining the advantage thereof andis approximately 10,000 ppm or less for preventing the maximumtemperature from being decreased and preventing the minimum temperaturefrom being increased. A more desirable ratio thereof ranges fromapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to suit for a device of a guest host (GH) mode. Adesirable ratio of the dye ranges from approximately 0.01% by weight toapproximately 10% by weight. An antifoaming agent such as dimethylsilicone oil or methylphenyl silicone oil is mixed with the compositionfor preventing foaming. A desirable ratio of the antifoaming agent isapproximately 1 ppm or more for obtaining the advantage thereof and isapproximately 1,000 ppm or less for preventing display failure fromoccurring. A more desirable ratio thereof ranges from approximately 1ppm to approximately 500 ppm.

Seventh, the preparation methods of the component compounds will beexplained. These compounds can be prepared by known methods. Thepreparation method will be exemplified below. The compound (1) isprepared by the method disclosed in JP H11-116512A/1999. The compound(2) is prepared by the method disclosed in H2-237949 A/1990. Thecompound (3-1) is prepared by the method disclosed in JP S57-114532A/1982. The compound (3-2) is prepared by the method disclosed in JPH2-501071 A/1990. The compound (4-2) is prepared by the method disclosedin JP S60-51135 A/1985. The antioxidant is commercially available. Thecompound (6), wherein n is 1, is available, for example, fromSigma-Aldrich, Corporation. The compound (6), wherein n is 7, isprepared by the method disclosed in U.S. Pat. No. 3,660,505.

The compounds for which preparation methods were not described above canbe prepared according to the methods described in ORGANIC SYNTHESES(John Wiley & Sons, Inc.), ORGANIC REACTIONS (John Wiley & Sons, Inc.),COMPREHENSIVE ORGANIC SYNTHESIS (Pergamon Press), NEW EXPERIMENTALCHEMISTRY COURSE (Shin Jikken Kagaku Kouza) (Maruzen, Inc.), and soforth. The composition is prepared according to known methods using thecompounds thus obtained. For example, the component compounds are mixedand dissolved in each other by heating.

Last, use of the composition will be explained. Most of the compositionshave a minimum temperature of approximately −10° C. or less, a maximumtemperature of 70° C. or more, and an optical anisotropy ofapproximately 0.07 to approximately 0.20. The device containing thecomposition has a large voltage holding ratio. The composition issuitable for an AM device. The composition is suitable especially for anAM device of a transmission type. The composition having an opticalanisotropy of approximately 0.08 to approximately 0.25 and furtherhaving an optical anisotropy of approximately 0.10 to approximately 0.30may be prepared by controlling ratios of the component compounds or bymixing other liquid crystal compounds. The composition can be used as acomposition having a nematic phase and as an optically activecomposition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for an AM device or a PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA, and soforth. It is especially desirable to use the composition for an AMdevice having a mode of VA or IPS. These devices may be of a reflectiontype, a transmission type or a semi-transmission type. It is desirableto use the composition for a device of a transmission type. It can beused for an amorphous silicon-TFT device or a polycrystal silicon-TFTdevice. The composition is also usable for a nematic curvilinear alignedphase (NCAP) device prepared by microcapsulating the composition, andfor a polymer dispersed (PD) device in which a three dimensionalnet-work polymer is formed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

When a sample was a composition, it was measured as it was, and theobtained value is described here. When a sample was a compound, a samplefor measurement was prepared by mixing 15% by weight of the compound and85% by weight of mother liquid crystals. A value of characteristic ofthe compound was calculated by extrapolating from a value obtained bymeasurement. Namely: (extrapolated value)={(value measured forsample)−0.85×(value measured for mother liquid crystals)}/0.15. When asmectic phase (or crystals) separated out at this ratio at 25° C., aratio of the compound and mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight), (1% by weight/99% by weight), respectively. Values for amaximum temperature, optical anisotropy, viscosity, and dielectricanisotropy of the compound were obtained by the extrapolation.

The composition of the mother liquid crystals is as shown below.

Measurement of the value of the characteristics was carried outaccording to the following methods. Most methods are described in theStandard of Electric Industries Association of Japan, EIAJ.ED-2521 A orthose with some modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point measuring apparatus equipped with apolarizing microscope and was heated at the rate of 1° C. per minute. Atemperature was measured when a part of the sample began to change froma nematic phase into an isotropic liquid. A higher limit of atemperature range of a nematic phase may be abbreviated to “a maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in a glass vial and then kept in a freezer attemperatures of 0° C., −10° C., −20° C., −30° C., and −40° C. for tendays, respectively, and a liquid crystal phase was observed. Forexample, when the sample remained in a nematic phase at −20° C. andchanged to crystals or a smectic phase at −30° C., Tc was expressed as≦−20° C. A lower limit of a temperature range of a nematic phase may beabbreviated to “a minimum temperature.”

Viscosity (η; measured at 20° C., mPa·s): The viscosity was measured bymeans of an E-type viscometer.

Optical Anisotropy (refractive anisotropy An; measured at 25° C.):Measurement was carried out with an Abbe refractometer mounting apolarizing plate on an ocular using a light at a wavelength of 589 nm.The surface of a main prism was rubbed in one direction, and then asample was dropped on the main prism. The refractive index (n∥) wasmeasured when the direction of a polarized light was parallel to that ofthe rubbing. The refractive index (n⊥) was measured when the directionof a polarized light was perpendicular to that of the rubbing. A valueof optical anisotropy was calculated from the equation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δε; measured at 25° C.): The value of thedielectric anisotropy was calculated from the equation: Δε=ε∥−ε⊥. Thevalues of dielectric constant (ε∥ and ε⊥) were measured in the followingmanner.

(1) Measurement of dielectric constant (ε∥): A solution ofoctadecyltriethoxy silane (0.16 mL) dissolved in ethanol (20 mL) wascoated on a glass substrate having been well cleaned. The glasssubstrate was rotated with a spinner and then heated to 150° C. for 1hour. A sample was charged in a VA device having a distance (cell gap)of 4 μm between two sheets of the glass substrates, and the device wassealed with an adhesive capable of being cured with ultraviolet light.Sine waves (0.5 V, 1 kHz) were applied to the device, and after lapsingtwo seconds, a dielectric constant (ε∥) in the major axis direction ofthe liquid crystal molecule was measured.

(2) Measurement of dielectric constant (ε⊥): Polyimide was coated on aglass substrate having been well cleaned. The glass substrate was baked,and the resulting orientation film was subjected to a rubbing treatment.A sample was charged in a TN device having a distance between two sheetsof the glass substrates (cell gap) of 9 μm and a twisted angle of 80°.Sine waves (0.5 V, 1 kHz) were applied to the device, and after lapsingtwo seconds, a dielectric constant (ε⊥) in the minor axis direction ofthe liquid crystal molecule was measured.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with LCD Evaluation System Model LCD-5100 made by Otsuka ElectronicsCo., Ltd. The light source was a halogen lamp. A sample was poured intoa VA device of a normally black mode, in which a cell gap between twoglass plates was 4 μm, and a rubbing direction was antiparallel, and thedevice was sealed with a UV curing adhesive. The voltage to be appliedonto the device (60 Hz, rectangular waves) was increased stepwise by0.02 V starting from 0 V up to 20 V. During the stepwise increasing, thedevice was irradiated with light in a perpendicular direction, and anamount of the light passing through the device was measured. Avoltage-transmission curve was prepared, in which a maximum amount of alight corresponded to 100% transmittance, a minimum amount of a lightcorresponded to 0% transmittance. Threshold voltage is a value at 10%transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass plates is 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive which is polymerized by theirradiation of an ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). The decreasingvoltage was measured for 16.7 milliseconds with High Speed Voltmeter andthe area A between a voltage curve and a horizontal axis in a unit cyclewas obtained. The area B was an area without decreasing. The voltageholding ratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass plates is 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive which is polymerized by theirradiation of an ultraviolet light. The TN device was applied andcharged with pulse voltage (60 microseconds at 5 V). The decreasingvoltage was measured for 16.7 milliseconds with High Speed Voltmeter andthe area A between a voltage curve and a horizontal axis in a unit cyclewas obtained. The area B was an area without decreasing. The voltageholding ratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): After irradiatingwith ultraviolet light, a voltage holding ratio was measured to evaluatestability to ultraviolet light. A composition having large VHR-3 has alarge stability to ultraviolet light. A TN device used for measurementhas a polyimide-alignment film and the cell gap is 5 μm. A sample waspoured into the device, and then the device was irradiated with lightfor 20 minutes. The light source was a superhigh voltage mercury lampUSH-500D (produced by Ushio, Inc.), and the distance between the deviceand the light source is 20 cm. In measurement of VHR-3, a decreasingvoltage was measured for 16.7 milliseconds. The VHR-3 is desirably 90%or more, and more desirably 95% or more.

Voltage holding Ratio (VHR-4; measured at 25° C.; %): The voltageholding ratio was measured after heating an TN device having a samplepoured therein in a constant-temperature bath at 80° C. for 500 hours toevaluate stability to heat. A composition having a large VHR-4 has alarge stability to heat. In measurement of VHR-4, a decreasing voltagewas measured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; ms): Measurement was carried outwith LCD Evaluation System Model LCD-5100 made by Otsuka ElectronicsCo., Ltd. Light source is a halogen lamp. Low-pass filter was set at 5kHz. A sample was poured into a VA device of a normally black mode, inwhich a cell gap between two glass plates was 4 μm, and a rubbingdirection was antiparallel, and the device was sealed with a UV curingadhesive. Rectangle waves (60 Hz, 10 V, 0.5 seconds) were applied to thedevice. During application, the device was irradiated with light in aperpendicular direction, and an amount of the light passing through thedevice was measured. A maximum amount of a light corresponds to 100%transmittance, and a minimum amount of a light corresponds to 0%transmission. The response time is a period of time required for thechange in transmittance from 90% to 10% (fall time: ms).

Specific Resistance (ρ; measured at 25° C.; Ωcm): 1.0 mL of a sample wascharged in a vessel equipped with electrodes. A direct current voltageof 10 V was applied to the vessel, and after lapsing 10 second from theapplication of voltage, the direct electric current was measured. Thespecific resistance was calculated by the equation: (specificresistance)={(voltage)×(electric capacity of vessel)}/{(directcurrent)×(dielectric constant of vacuum)}.

Gas Chromatographic Analysis: A Gas Chromatograph Model GC-14B made byShimadzu was used for measurement. The carrier gas was helium (2milliliters per minute). An evaporator and a detector (FID) were set upat 280° C. and 300° C., respectively. Capillary column DB-1 (length 30meters, bore 0.32 millimeters, film thickness 0.25 micrometers,dimethylpolysiloxane as stationary phase, no polarity) made by AgilentTechnologies, Inc. was used for the separation of the componentcompound. After the column had been kept at 200° C. for 2 minutes, itwas further heated to 280° C. at the rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and 1 microliterof the solution was injected into the evaporator. The recorder used wasChromatopac Model C-R5A made by Shimadzu or its equivalent. The gaschromatogram obtained showed a retention time of a peak and a peak areacorresponding to the component compound.

Solvents for diluting the sample may also be chloroform, hexane, and soforth. The following capillary columns may also be used for theseparation of the component compound: HP-1 made by Agilent TechnologiesInc. (length 30 meters, bore 0.32 millimeters, film thickness 0.25micrometers), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeters, film thickness 0.25 micrometers), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeters, filmthickness 0.25 micrometers). In order to prevent compound peaks fromoverlapping, a capillary column CBP1-M50-025 (length 50 meters, bore0.25 millimeters, film thickness 0.25 micrometers) made by ShimadzuCorporation may be used.

The ratios of the liquid crystal compounds contained in the compositioncan also be calculated in the following manner. A liquid crystalcompound can be detected by gas chromatography. An area ratio of peakson a gas chromatogram corresponds to a ratio (molar number) of liquidcrystal compounds. In the case where the aforementioned capillarycolumns are used, correction coefficients of the liquid crystalcompounds can be regarded as 1. Accordingly, the ratio (% by weight) ofliquid crystal compounds is calculated from the area ratio of peaks.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsdescribed in the Comparative Examples and the Examples are expressed bythe symbols according to the definition in Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. The parenthesized numbernext to the symbolized compounds in the Examples corresponds to thenumber of the desirable compound. The symbol “(−)” means other liquidcrystal compound. A ratio (percentage) of a liquid crystal compound ispercentage by weight (% by weight) based on the total weight of a liquidcrystal composition.

TABLE 3 Method of Description of Compound using Symbols R—(A₁)—Z₁— . . .—Z_(n)—(A_(n))—R′ 1) Left Terminal Group R— Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO- C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V-CH₂═CH—C_(n)H_(2n)— Vn- CF₂═CH— VFF- CF₂═CH—C_(n)H_(2n)— VFFn- 2) RingStructure —An— Symbol

B

B(2F)

B(3F)

B(2F,3F)

B(2F,5F)

H 3) Bonding group —Zn— Symbol —C₂H₄— 2 —CH═CH— V —COO— E —OCO— Er 4)Right Terminal Group —R′ Symbol —C_(n)H_(2n+1) -n —OC_(n)H_(2n+1) -On—CH═CH₂ -V —CH═CHC_(n)H_(2n+1) -Vn —F -F —Cl -CL 5) Example ofDescription Example 1

Example 2

Example 3

Comparative Example 1

Example 6 was chosen from the compositions disclosed in JP H9-183974A/1997. The basis is that the composition contains the compounds (1) and(4-2). The components and characteristics of the composition were asfollows.

3-BB(2F,3F)-O2 (1-1-1) 15% 3-BB(2F,3F)-O4 (1-1-1) 18% 4-HEB(2F,3F)-O2(—) 4% 2-BB(3F)B-3 (4-2-1-1) 11% 2-BBB(2F,3F)-3 (—) 15% 3-BB(2F)B(2F)-CL(—) 10% 5-BB(2F)B(2F)-CL (—) 15% 5-HBBH-3 (—) 3% 5-HBBH-5 (—) 3%3-HB(3F)BH-3 (—) 3% 5-HB(3F)BH-3 (—) 3%

NI=87.6° C.; Tc≦−20° C.; Δn=0.212; Δε=−2.6; η=56.6 mPa·s.

Comparative Example 2

Example 20 was chosen from the compositions disclosed in JP H11-116512A/1999. The basis is that the composition contains the compounds (1) and(3-2). The components and characteristics of the composition were asfollows.

3-BB(2F,3F)-O3 (1-1-1) 15% 5-BB(2F,3F)-O5 (1-1-1) 15% 5-BB(2F,3F)B-O6(3-2-1) 15% 5-BB(2F,3F)B-O8 (3-2-1) 15% 3-HB-O1 (—) 15% 3-HB-O2 (—) 15%3-HB(3F)BH-3 (—) 4% 5-HB(3F)BH-3 (—) 3% 5-HB(3F)BH-5 (—) 3%

NI=82.0° C.; Tc≦0° C.; Δn=0.170; Δε=−1.7.

Comparative Example 3

Example 4 was chosen from the compositions disclosed in JP 2003-327965A/2003. The basis is that the composition contains the compounds (1),(3-1), (3-2) and (4-1). The components and characteristics of thecomposition were as follows.

3-BB(2F,3F)-O3 (1-1-1) 8% 5-BB(2F,3F)-O5 (1-1-1) 8% 3-BB(2F)B(2F)-F (—)8% 1-BB-2V (—) 4% 1-BB-2V1 (—) 6% 3-HBB-2 (4-1-1-1) 6% 2-HBB(2F,3F)-O2(3-1-1-1) 9% 3-HBB(2F,3F)-O2 (3-1-1-1) 9% 2-BB(2F,3F)B-3 (3-2-1-1) 10%2-BB(2F)B(2F,3F)-1 (—) 8% 3-BB(2F)B(2F,3F)-1 (—) 8% 2-BB(2F)B(2F,3F)-O4(—) 8% 3-BB(2F)B(2F,3F)-O4 (—) 8%

NI=88.0° C.; Tc≦−10° C.; Δn=0.206; Δε=−3.2; Vth=2.30 V.

Example 1

3-BB(2F,3F)-O2 (1-1-1) 24% 5-BB(2F,3F)-O2 (1-1-1) 24% 5-HBB(3F)B-2(2-1-1) 8% 5-HBB(3F)B-3 (2-1-1) 8% 3-HBB(2F,3F)-O2 (3-1-1-1) 18%5-HBB(2F,3F)-O2 (3-1-1-1) 18%

NI=104.8° C.; Tc≦−20° C.; Δn=0.188; Δε=−5.4; Vth=1.72 V; η=45.3 mPa·s;VHR-1=99.1%; VHR-2=98.1%; VHR-3=97.9%.

Example 2

The composition of Example 2 had a large negative dielectric anisotropyand a low minimum temperature of a nematic phase as compared to thecomposition of Comparative Example 2.

3-B2B(2F,3F)-O2 (1-2-1) 22% 5-B2B(2F,3F)-O2 (1-2-1) 22% 5-HBB(3F)B-2(2-1-1) 8% 5-HBB(3F)B-3 (2-1-1) 8% 3-HBB(2F,3F)-O2 (3-1-1-1) 20%5-HBB(2F,3F)-O2 (3-1-1-1) 20%

NI=90.4° C.; Tc≦−20° C.; Δn=0.163; Δε=−4.9; Vth=1.80 V; η=42.1 mPa·s;VHR-1=99.2%; VHR-2=98.3%; VHR-3=98.1%.

Example 3

The composition of Example 3 had a large negative dielectric anisotropyand a low minimum temperature of a nematic phase as compared to thecomposition of Comparative Example 2.

3-BB(2F,3F)-O2 (1-1-1) 15% 5-BB(2F,3F)-O2 (1-1-1) 15% 3-B2B(2F,3F)-O2(1-2-1) 10% 5-B2B(2F,3F)-O2 (1-2-1) 10% 5-HBB(3F)B-2 (2-1-1) 8%5-HBB(3F)B-3 (2-1-1) 8% 3-HBB(2F,3F)-O2 (3-1-1-1) 17% 5-HBB(2F,3F)-O2(3-1-1-1) 17%

NI=92.5° C.; Tc≦−20° C.; Δn=0.176; Δε=−5.2; Vth=1.76 V; η=43.4 mPa·sVHR-1=99.0%; VHR-2=98.1%; VHR-3=98.0%.

Example 4

The composition of Example 4 had a large negative dielectric anisotropyand a low minimum temperature of a nematic phase as compared to thecomposition of Comparative Example 2.

3-BB(2F,3F)-O2 (1-1-1) 23% 5-BB(2F,3F)-O2 (1-1-1) 23% 5-HBB(3F)B-2(2-1-1) 10% 5-HBB(3F)B-3 (2-1-1) 10% 3-BB(2F,3F)B-1 (3-2-1-1) 5%3-BB(2F,3F)B-2 (3-2-1-1) 9% 4-BB(2F,3F)B-2 (3-2-1-1) 10% 5-BB(2F,3F)B-2(3-2-1-1) 10%

NI=91.6° C.; Tc≦−20° C.; Δn=0.212; Δε=−3.6; Vth=2.08 V; η=36.9 mPa·s;VHR-1=99.2%; VHR-2=98.3%; VHR-3=98.0%.

Example 5

3-B2B(2F,3F)-O2 (1-2-1) 18% 5-B2B(2F,3F)-O2 (1-2-1) 18% 5-HBB(3F)B-2(2-1-1) 12% 5-HBB(3F)B-3 (2-1-1) 12% 3-BB(2F,3F)B-2 (3-2-1-1) 10%3-BB(2F,3F)B-3 (3-2-1-1) 5% 4-BB(2F,3F)B-2 (3-2-1-1) 10% 5-BB(2F,3F)B-2(3-2-1-1) 10% 5-BB(2F,3F)B-3 (3-2-1-1) 5%

NI=91.1° C.; Tc≦−20° C.; Δn=0.202; Δε=−2.8; Vth=2.19 V; η=36.0 mPa·s;VHR-1=99.2%; VHR-2=98.2%; VHR-3=98.2%.

Example 6

The composition of Example 6 had a large negative dielectric anisotropyand a small viscosity as compared to the composition of ComparativeExample 1.

3-BB(2F,3F)-O2 (1-1-1) 15% 5-BB(2F,3F)-O2 (1-1-1) 15% 3-B2B(2F,3F)-O2(1-2-1) 11% 5-B2B(2F,3F)-O2 (1-2-1) 10% 5-HBB(3F)B-2 (2-1-1) 12%5-HBB(3F)B-3 (2-1-1) 12% 3-BB(2F,3F)B-2 (3-2-1-1) 5% 4-BB(2F,3F)B-2(3-2-1-1) 10% 5-BB(2F,3F)B-2 (3-2-1-1) 10%

NI=84.2° C.; Tc≦−20° C.; Δn=0.197; Δε=−3.6; Vth=2.02 V; η=35.7 mPa·s;VHR-1=99.1%; VHR-2=98.1%; VHR-3=97.9%.

Example 7

5-BB(2F,3F)-1 (1-1) 5% 3-BB(2F,3F)-O2 (1-1-1) 15% 5-BB(2F,3F)-O2 (1-1-1)15% 5-HBB(3F)B-2 (2-1-1) 7% 5-HBB(3F)B-3 (2-1-1) 8% 2-HBB(2F,3F)-O2(3-1-1-1) 5% 3-HBB(2F,3F)-O1 (3-1-1-1) 5% 3-HBB(2F,3F)-O2 (3-1-1-1) 10%3-HBB(2F,3F)-O3 (3-1-1-1) 5% 3-BB(2F,3F)B-2 (3-2-1-1) 10% 4-BB(2F,3F)B-2(3-2-1-1) 10% 5-BB(2F,3F)B-2 (3-2-1-1) 5%

NI=106.3° C.; Tc≦−20° C.; Δn=0.204; Δε=−4.2; Vth=1.92 V; η=43.8 mPa·s;VHR-1=99.1%; VHR-2=98.2%; VHR-3=98.1%.

Example 8

VFF2-BB(2F,3F)-O2 (1-1) 5% V2-BB(2F,3F)-O2 (1-1) 5% 3-BB(2F,3F)-O2(1-1-1) 15% 5-BB(2F,3F)-O2 (1-1-1) 15% 5-HBB(3F)B-2 (2-1-1) 5%5-HBB(3F)B-3 (2-1-1) 5% 2-HBB(2F,3F)-O2 (3-1-1-1) 5% 3-HEBB(2F,3F)-O2(3-1) 5% 3-HBEB(2F,3F)-O2 (3-1) 5% 5-HBErB(2F,3F)-O2 (3-1) 5%V-HBB(2F,3F)-O2 (3-1-1) 5% 5-H2BB(2F,3F)-O2 (3-1-2) 5% 5-HB2B(2F,3F)-O2(3-1-3) 5% 3-BErB(2F,3F)B-2 (3-2) 5% 3-B2B(2F,3F)B-2 (3-2-2) 5%3-B2B(2F,3F)2B-2 (3-2-3) 5%

NI=100.0° C.; Tc≦−20° C.; Δn=0.186; Δε=−4.9; Vth=1.79 V; η=44.4 mPa·s;VHR-1=99.2%; VHR-2=98.2%; VHR-3=98.1%.

Example 9

The composition of Example 9 had a large negative dielectric anisotropyand a low minimum temperature of a nematic phase as compared to thecomposition of Comparative Example 3.

3-BB(2F,3F)-O2 (1-1-1) 23% 5-BB(2F,3F)-O2 (1-1-1) 23% 5-HBB(3F)B-2(2-1-1) 7% 5-HBB(3F)B-3 (2-1-1) 7% 3-HBB(2F,3F)-O2 (3-1-1-1) 15%5-HBB(2F,3F)-O2 (3-1-1-1) 15% 3-HBB-2 (4-1-1-1) 7% 5-HBB-2 (4-1-1-1) 3%

NI=105.2° C.; Tc≦−20° C.; Δn=0.186; Δε=−4.6; Vth=1.85 V; η=42.4 mPa·s;VHR-1=99.2%; VHR-2=98.3%; VHR-3=98.1%.

Example 10

3-BB(2F,3F)-O2 (1-1-1) 24% 5-BB(2F,3F)-O2 (1-1-1) 24% 5-HBB(3F)B-2(2-1-1) 7% 5-HBB(3F)B-3 (2-1-1) 7% 3-HBB(2F,3F)-O2 (3-1-1-1) 14%5-HBB(2F,3F)-O2 (3-1-1-1) 14% 2-BB(3F)B-3 (4-2-1-1) 10%

NI=98.6° C.; Tc≦−20° C.; Δn=0.196; Δε=−4.9; Vth=1.80 V; η=42.8 mPa·s;VHR-1=99.1%; VHR-2=98.1%; VHR-3=98.0%.

Example 11

3-BB(2F,3F)-O2 (1-1-1) 24% 5-BB(2F,3F)-O2 (1-1-1) 24% 5-HBB(3F)B-2(2-1-1) 6% 5-HBB(3F)B-3 (2-1-1) 6% 3-HBB(2F,3F)-O2 (3-1-1-1) 11%5-HBB(2F,3F)-O2 (3-1-1-1) 11% 3-HBB-2 (4-1-1-1) 8% 2-BB(3F)B-3 (4-2-1-1)5% 3-BB(2F,5F)B-3 (4-2-2) 5%

NI=94.6° C.; Tc≦−20° C.; Δn=0.191; Δε=−4.0; Vth=1.94 V; η=40.8 mPa·s;VHR-1=99.2%; VHR-2=98.3%; VHR-3=98.2%.

Example 12

3-BB(2F,3F)-O2 (1-1-1) 24% 5-BB(2F,3F)-O2 (1-1-1) 24% 5-HBB(3F)B-2(2-1-1) 7% 5-HBB(3F)B-3 (2-1-1) 7% 3-HBB(2F,3F)-O2 (3-1-1-1) 16%5-HBB(2F,3F)-O2 (3-1-1-1) 17% 7-HB-1 (—) 5%

NI=95.1° C.; Tc≦−20° C.; Δn=0.180; Δε=−5.2; Vth=1.78 V; η=42.6 mPa·s;VHR-1=99.2%; VHR-2=98.2%; VHR-3=98.1%.

Example 13

3-B2B(2F,3F)-O2 (1-2-1) 22% 5-B2B(2F,3F)-O2 (1-2-1) 22% 5-HBB(3F)B-2(2-1-1) 6% 5-HBB(3F)B-3 (2-1-1) 6% 3-HBB(2F,3F)-O2 (3-1-1-1) 20%5-HBB(2F,3F)-O2 (3-1-1-1) 20% 1O1-HBBH-5 (—) 4%

NI=90.8° C.; Tc≦−20° C.; Δn=0.160; Δε=−4.8; Vth=1.81 V; η=43.2 mPa·s;VHR-1=99.1%; VHR-2=98.3%; VHR-3=98.0%.

Example 14

3-BB(2F,3F)-O2 (1-1-1) 15% 5-BB(2F,3F)-O2 (1-1-1) 15% 3-B2B(2F,3F)-O2(1-2-1) 10% 5-B2B(2F,3F)-O2 (1-2-1) 10% 5-HBB(3F)B-2 (2-1-1) 7%5-HBB(3F)B-3 (2-1-1) 8% 3-HBB(2F,3F)-O2 (3-1-1-1) 15% 5-HBB(2F,3F)-O2(3-1-1-1) 15% 3-HB-O2 (—) 5%

NI=85.4° C.; Tc≦−20° C.; Δn=0.170; Δε=−5.0; Vth=1.74 V; η=41.1 mPa·s;VHR-1=99.1%; VHR-2=98.1%; VHR-3=98.1%.

Example 15

3-BB(2F,3F)-O2 (1-1-1) 22% 5-BB(2F,3F)-O2 (1-1-1) 22% 5-HBBB(2F)-2 (2)5% 5-HBB(3F)B-O2 (2) 4% 5-HBB(3F)B-2 (2-1-1) 7% 3-HBB(2F,3F)-O2(3-1-1-1) 10% 5-HBB(2F,3F)-O2 (3-1-1-1) 10% 1V-HBB-2 (4-1-1) 5%2-BBB(2F)-3 (4-2) 5% V2-BB(3F)B-1 (4-2-1) 5% 1-BB(3F)B-2V (4-2-1) 5%

NI=102.3° C.; Tc≦−20° C.; Δn=0.203; Δε=−3.0; Vth=2.18 V; η=41.6 mPa·s;VHR-1=99.0%; VHR-2=98.1%; VHR-3=97.9%.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the disclosure has beenmade only by way of example, and that numerous changes in the conditionsand order of steps can be resorted to by those skilled in the artwithout departing from the spirit and scope of the invention.

1. A liquid crystal composition having a negative dielectric anisotropycomprising two components, wherein the first component is at least onecompound selected from the group of compounds represented by Formula(1), and the second component is at least one compound selected from thegroup of compounds represented by Formula (2):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; Z¹ is a single bond or —(CH₂)₂—; and Y¹ and Y² are eachindependently hydrogen or fluorine.
 2. A liquid crystal compositionhaving a negative dielectric anisotropy comprising two components,wherein the first component is at least one compound selected from thegroup of compounds represented by Formulas (1-1) and (1-2), and thesecond component is at least one compound selected from the group ofcompounds represented by Formula (2-1):

wherein R³ and R⁵ are each independently alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons; and R⁴ is alkyl having 1 to 12 carbonsor alkoxy having 1 to 12 carbons.
 3. The liquid crystal compositionaccording to claim 2, wherein the first component is at least onecompound selected from the group of compounds represented by Formula(1-1), and the second component is at least one compound selected fromthe group of compounds represented by Formula (2-1).
 4. The liquidcrystal composition according to claim 2, wherein the first component isat least one compound selected from the group of compounds representedby Formula (1-2), and the second component is at least one compoundselected from the group of compounds represented by Formula (2-1). 5.The liquid crystal composition according to claim 2, wherein the firstcomponent is a mixture of at least one compound selected from the groupof compounds represented by Formula (1-1) and at least one compoundselected from the group of compounds represented by Formula (1-2), andthe second component is at least one compound selected from the group ofcompounds represented by Formula (2-1).
 6. The liquid crystalcomposition according to claim 1, wherein the ratio of the firstcomponent is from approximately 25% by weight to approximately 65% byweight and the ratio of the second component is from approximately 5% byweight to approximately 40% by weight, based on the total weight of theliquid crystal composition.
 7. The liquid crystal composition accordingto claim 2, wherein the ratio of the first component is fromapproximately 25% by weight to approximately 65% by weight and the ratioof the second component is from approximately 5% by weight toapproximately 40% by weight, based on the total weight of the liquidcrystal composition.
 8. The liquid crystal composition according toclaim 1, wherein the composition further comprises at least one compoundselected from the group of compounds represented by Formulas (3-1) and(3-2) as a third component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; Ring A is 1,4-cyclohexylene or 1,4-phenylene; and Z² and Z³are each independently a single bond, —(CH₂)₂—, —CH═CH—, —COO— or —OCO—.9. The liquid crystal composition according to claim 2, wherein thecomposition further comprises at least one compound selected from thegroup of compounds represented by Formulas (3-1) and (3-2) as a thirdcomponent:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; Ring A is 1,4-cyclohexylene or 1,4-phenylene; and Z² and Z³are each independently a single bond, —(CH₂)₂—, —CH═CH—, −COO— or —OCO—.10. The liquid crystal composition according to claim 8, wherein thethird component is at least one compound selected from the group ofcompounds represented by Formula (3-1).
 11. The liquid crystalcomposition according to claim 8, wherein the third component is atleast one compound selected from the group of compounds represented byFormula (3-2).
 12. The liquid crystal composition according to claim 8,wherein the third component is a mixture of at least one compoundselected from the group of compounds represented by formula (3-1) and atleast one compound selected from the group of compounds represented byFormula (3-2).
 13. The liquid crystal composition according to claim 1,wherein the composition further comprises at least one compound selectedfrom the group of compounds represented by Formulas (3-1-1) and (3-2-1)as a third component:

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons; and R⁴ is alkyl having 1 to 12 carbons or alkoxy having 1 to 12carbons.
 14. The liquid crystal composition according to claim 2,wherein the composition further comprises at least one compound selectedfrom the group of compounds represented by Formulas (3-1-1) and (3-2-1)as a third component:

wherein R³ is alkyl having 1 to 12 carbons or alkenyl having 2 to 12carbons; and R⁴ is alkyl having 1 to 12 carbons or alkoxy having 1 to 12carbons.
 15. The liquid crystal composition according to claim 14,wherein the third component is at least one compound selected from thegroup of compounds represented by Formula (3-1-1).
 16. The liquidcrystal composition according to claim 8, wherein the ratio of the thirdcomponent is from approximately 10% by weight to approximately 65% byweight based on the total weight of the liquid crystal composition. 17.The liquid crystal composition according to claim 9, wherein the ratioof the third component is from approximately 10% by weight toapproximately 65% by weight based on the total weight of the liquidcrystal composition.
 18. The liquid crystal composition according toclaim 1, wherein the composition further comprises at least one compoundselected from the group of compounds represented by Formulas (4-1) and(4-2) as a fourth component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; and Y¹, Y² and Y³ are each independently hydrogen orfluorine.
 19. The liquid crystal composition according to claim 2,wherein the composition further comprises at least one compound selectedfrom the group of compounds represented by Formulas (4-1) and (4-2) as afourth component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having from 1 to 12 carbons, alkenyl having 2 to 12 carbons oralkenyl having 2 to 12 carbons, arbitrary hydrogen of which are replacedby fluorine; and Y¹, Y² and Y³ are each independently hydrogen orfluorine.
 20. The liquid crystal composition according to claim 18,wherein the fourth component is at least one compound selected from thegroup of compounds represented by Formula (4-2).
 21. The liquid crystalcomposition according to claim 1, wherein the composition furthercomprises at least one compound selected from the group of compoundsrepresented by Formulas (4-1-1) and (4-2-1) as a fourth component:

wherein R³ and R⁵ are each independently alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons.
 22. The liquid crystal compositionaccording to claim 2, wherein the composition further comprises at leastone compound selected from the group of compounds represented byFormulas (4-1-1) and (4-2-1) as a fourth component:

wherein R³ and R⁵ are each independently alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons.
 23. The liquid crystal compositionaccording to claim 21, wherein the fourth component is at least onecompound selected from the group of compounds represented by Formula(4-2-1).
 24. The liquid crystal composition according to claim 18,wherein the ratio of the fourth component is from approximately 5% byweight to approximately 30% by weight based on the total weight of theliquid crystal composition.
 25. The liquid crystal composition accordingto claim 19, wherein the ratio of the fourth component is fromapproximately 5% by weight to approximately 30% by weight based on thetotal weight of the liquid crystal composition.
 26. The liquid crystalcomposition according to claim 1, wherein the composition has a maximumtemperature of a nematic phase of approximately 70° C. or more, anoptical anisotropy (25° C.) at a wavelength of 589 nm of approximately0.10 or more, and a dielectric anisotropy (25° C.) at a frequency of 1kHz of approximately −2 or less.
 27. A liquid crystal display devicecomprising the liquid crystal composition according to claim
 1. 28. Theliquid crystal display device according to claim 27, wherein the liquidcrystal display device has an operation mode of a VA mode or an IPSmode, and has a driving mode of an active matrix mode.